Meet Ferry the Spaceship.
When you need a quick one-off delivery, Ferry is your chauffeur. We hired him because there is no traffic or possibility of collisions in space. This makes him excellently suited for the job: fast, reliable, and no driver's license required.
When this boat floors it, the first 100 km/s out of a planetary orbit are reached in less than a second. My trusty qalculater tells me that
> 100km/s /1s to gees
(100 kilometers/second) / (1 second) ≈ 10197.2 gees
Being used to tens or perhaps hundreds of gs at most, I thought my calculation had gone wrong, but no: with one earth g at ~9.8m/s², these 100km/s² aren't a mere ten of those, there is an extra kilo of them.
Ten thousand earth gravities. Fancy that pulling on your buttocks! Ferry's leap into interplanetary space is, however, no unparalleled feat. Desiring to put this number into context, my deep dive research (i.e., opening Wikipedia) landed me at this comparison table. Coming in at 10'400 g, a Mantis Shrimp's claw during predatory strike accelerates as fast as Ferry's six rocket engines.
The next entry of the table is also of Factorial relevance: the electronics in military artillery shells is rated up to 15'500 g. I am glad I haven't pushed a little harder! Poor Ferry, his electronics broken, völlig losgelöst
I hope this fun fact made your day just a little better :)
Thanks! Yes, I did not actually mean to suggest that this is faster than other people's ships, just that I measured this particular one which I think must be our highest thrusters-to-weight ratio (because it's not meant to be in continuous use but just express deliveries, it has a lot of time to recharge fuel and get sent ammo, so the other facilities are small). Based on this result, I'd assume that most people's starter ship would cause this bone-liquifying acceleration ^^
If you read or watched The Expanse, the answer to that would be Alex's juice!
Here in the real world, afaik the only answer that we currently know would work is antigravity tech, as in, some spacetime-bending object ahead of the ship. If you put planet earth in the nose cone of your space ship, you can push the ship about 9.8 m/s² faster than you otherwise could (because the travellers are 'attracted' forwards it (technically: at a standstill relative to spacetime) and thus doesn't experience that acceleration). Now you have the extra problem of accelerating an earth's worth of mass at the desired acceleration, but that's just an engineering/scaling issue right? :D